What Makes a Season?

I’ll be posting here regularly about community supported agriculture (CSA) and my own personal experiences with the tasty, organic produce from my local CSA.

Most CSA farms will offer their produce on a seasonal basis. Mine has a warm (March – July) and cool (October – January) delivery schedule with each season bringing a different batch of fresh fruits and veggies. Looking over my cold-weather basket of potatoes, turnips, and greens led me to wonder just what it was that separates the tomatoes I get in summer from my winter tubers. We all know that it’s best to buy foods that are in season, but why do fruits and vegetables have seasons in the first place?

Fruit or vegetable?

. . .

To understand seasonal produce, first you have to understand the difference between fruits and vegetables. We may lump them together, and sometimes get them confused, but what makes a fruit a fruit is what determines when it grows best. When we’re talking about edible produce, we usually refer to sweet plants as fruits and savory ones as vegetables, but botanists have more technical definitions.

In botany, a fruit is the tissue that surrounds the seed of a flowering plant. It protects the seed and plays a role in dispersal. This last part is important. It’s why fruits like strawberries and apples are so tasty—animals want to eat them, and when they do they carry the seeds far and wide.

Vegetables, on the other hand, are a bit more loosely defined. Generally, the term vegetable is used to describe any part of a plant that we eat that isn’t a fruit. These includes things like leaves (spinach, kale), roots (potatoes, beets), and stems (celery, fennel). Technically, many of the savory foods we call vegetables, including tomatoes, squash, and eggplants, are actually fruits.

When is the time to harvest?

So why does it matter whether we’re eating fruits or vegetables? In short, it’s because plants, like people, have limited resources to go around. There’s only so much water, nutrients, and energy a plant can invest in flowering, growing leaves, or sending out roots, which means you want to be harvesting from the plant when the part of the plant you’re interested in is at its peak.

Take fruits, for example. Most flowering plants will bear fruit that ripens in the summer or early fall because fruits are energy intensive, meaning it take a lot of sunlight for a plant to grow those apples, berries, or tomatoes. That’s why most of the garden plants we grow in the spring and summer are fruits: the long days full of sunlight and warm temperatures give the plant the energy it needs to flower and fruit. (There are of course exceptions to all these rules—plants are amazingly versatile and have developed all kinds of crazy life cycles to adapt to their environments. What we’re discussing here is generally true for most of the produce we consume regularly.)

When it comes to vegetables, though, flowering is the last thing a farmer wants. Once a vegetable starts flowering, it stops investing as much energy in its leaves, roots, and stems, which means that a celery stalk or turnip is going to go from big and juicy to weak and wilted. That’s why most vegetables are cold weather garden plants. Over the fall or winter months, plants store up energy in their leaves and roots in preparation for the spring, when they’ll have the sunlight they need to start producing seeds and fruit. So, as a farmer you want to harvest those parts of the plant when they’re at their peak, which means in the colder time period before they flower.

Why the “where” is important, too.

These guidelines generally define when we grow plants for food, but it’s where you live that will determine when fruits and vegetables are in season near you. Obviously, “cold” and “warm” happen at different times and to different degrees in different part of the U.S. and the world. That’s why farmers where I live in Texas are already harvesting vegetables like cauliflower and sweet potatoes in January, while most areas to the north are still snowed under. This variation is seasons is a big reason we can now get fresh fruit all winter long as strawberries, oranges, and bananas are imported from tropical regions.

The last issue that determines what’s in season near you is what’s native to your region. Obviously, if a plant evolved in a hot climate, it’s going to grow best in warmer temperatures, and plants from colder regions are going to do better at lower temperatures. Tropical fruits like citruses and bananas need hot, hot weather to fruit, which means you’re never going to get them to grow well outdoors in New England, but you can get tasty apples, which evolved in colder climates. If you want to know what’s in season in your area, check out this great Seasonal Ingredient Map from Epicurious that will show you what’s available state-by-state throughout the year.

Recipe of the week: Pickled eggs

I’ve always loved the sweet flavor and slightly unreal purple color of good pickled eggs, and this is a great basic recipe. You can change it up by adding extras like peppers or spices to the pickling mixture.

6 hard-boiled eggs

2 cups water

1 beet

1 cup cider vinegar

1/4 cup onion, sliced

1/3 cup sugar

1. Hard boil eggs. My fool-proof method is to place eggs and water in a small pot and bring to a boil, then turn off the heat and let them cook for fifteen minutes. Make sure to leave the pot covered or the water will get cold too fast.

2. In saucepan, boil beets in 2 cups of water until tender.

3. Add vinegar, onion, and sugar to the beets/beet juice and cook until onions are translucent, usually 5 – 10 minutes.

4. Remove vinegar and beet mixture from heat. While the mixture cools, peel eggs and place in glass container.

5. Cover eggs with vinegar and beet mixture. Seal and let sit for a few days, then enjoy!